transport in cells Flashcards
what is diffusion
the net movement of cells from an area of high concentration to low concentration
solute definition
substance that is being dissolved in the solvent
solvent definition
the substance that the solute dissolves in
solution definition
mixture of solute and solvent
factors which affect rate of diffusion
temperature
difference in concentration
surface area
another way of saying difference in concentration
concentration gradient
what will happen to the rate of diffusion of the concentration gradient is steep
it will occur quicker
how to calculate SA : V ratio
1) calculate surface area: length x length x 6
2) calculate volume: length x width x height
3) divide surface area by volume
relationship between increasing cube size and SA:V ratio
the smaller the cube, the larger the surface area to volume ratio
name the process which oxygen enters the skin cells
diffusion
advantage of large SA:V ratio
particles can diffuse quicker / more particles absorbed because more surface is exposed so particles can diffuse more efficiently.
why can bacteria rely on diffusion for gas exchange but animals need a transport system
bacteria have larger surface area to volume ratio tha animals. therefore easier for gas exchange. animals have smaller ratio which slows down diffusion alot and wouldn’t be able to reach all cells
how and why will a higher temperature affect diffusion
the higher temperature, the faster the rate of diffusion because particles gain more kinetic energy therefore they move around faster
advantages of a wall being one cell thick?
shorter diffusion pathway
describe how the lungs in mammals are adapted for diffusion
- good blood supply: maintain concentration gradeint
- millions of alveoli in each lung: large surface area
-alveolus wall only one cell thick: shorter diffusion pathway
describe how the small intestine is adapted for diffusion
-surface is folded to form villi: larger surface area
-good blood supply: maintain steep conc. gradient
-walls are one cell thick: short diffusion pathway
describe how the gills in fish are adapted for diffusion
-many gill filaments: provides larger surface area
-filaments are very thin: shorter diffusion pathway
-water is pumped over gills: maintains steep conc. gradient
describe how the roots and leaves in plants are adpated for diffusion
many roots - larger surface area for oxygen to be absorbed
root haircells are long: larger SA:V ratio
root hair cells are thin: shorter diffusion pathway
what is osmosis
the movement of water paarticles from an area of high water potential to an area of low water potential through a partially permeable membrane
what happens if the concentration is the same on both sides
no net movement of any particles as the concentration/water potential is equal
how to calculate percentage change
final - initial / inital x 100
why do we use percentage change
makes our answers easy to compare / comparitive
controls or improving the potato cylinder practical
-making sure the potato cylinder is the same size so SA:V ratio wont be affected
-not contaminating any solutions
-making sure cylinders are left in for the same amount of time
-making sure temperature of solution is the same
-you can repeaet experiment several times
why is it important to dry the potato
to make sure there isn’t any excess water affecting the mass of the potato
what does a larger SA:V ratio mean in the potato experiment
more water absorbed
what is active transport
when particles move against the concentration gradient through a membrane and it requires energy
(low to high)
difference between active transport and diffusion
active transport requires energy whereas diffusion is a passive process
in A.T particles move against the concentration gradient where as particles in diffusion move from an area of high to low concentration
